Servo gear reduction idea

[Terry G]

I am working on a gear reduction system for my 3000 RPM with 20oz-in torque globe servo motors I want to use on my cnc plasma table I am designing.

I plan on attaching a 17 tooth timing belt pulley with .1181" (3mm) pitch on the motor shaft. Then I will go to a 72 tooth pulley giving me 4.2:1 reduciton. On this same shaft I will attach another 17 tooth pulley and go to a third and final shaft with a 72 tooth pulley. This would give me a total of 17.64:1 reduction. I plan on using a .345" wide belt. This should theoretically give me a final torque of 350 oz-in minus any loss. And backlash should be to a minimal. I found these items from http://www.econobelt.com/Q460/RFQ/de...g_1-118_1.html, and they seem to be the same pulley / belt combo used on my cnc mill gear reduction.

Then the output of the third shaft will drive my jackshaft which will attach to either side of my gantry. The table will be fairly small, around 3x3, and I am designing the gantry to be as light as possible yet still rigid enough not to flex under its own weight during operation.

The concern I have is will these timing belts I chose handle the higher torque and accelration and deceleration of the gantry. I am especially worried about when the gantry is moving at 300ipm, and it needs to instantly change direction, will the timing belts slip on the pulleys? I tried to space the pulleys apart far enough so the smaller pulley had about 40% of it's teeth enganged with the bigger pulley having about 60% (these are just a rough estimate from my drawings). I have zero experience using these types of timing belts. I just went off my cnc mill design, though it only as a 2.8:1 reduction on the belt, not 17.64:1. And the cnc mill has far less inertia it has to stop and accelerate.

Hope someone can tell me if this would absolutely not work (then I won't even spend the money on a prototype), or would work great. But I am willing to build a prototype and try it if people think it might work.

Any other ideas along these lines would be appreciated also. Thanks.